private IEnumerable<BookCollection> GetBookCollectionsOnce()
{
var editableCllection = _bookCollectionFactory(_pathToLibrary, BookCollection.CollectionType.TheOneEditableCollection);
_currentEditableCollectionSelection.SelectCollection(editableCllection);
yield return editableCllection;
foreach (var bookCollection in _sourceCollectionsList.GetSourceCollectionsFolders())
yield return _bookCollectionFactory(bookCollection, BookCollection.CollectionType.SourceCollection);
}